The water is said to heal sore eyes, and the saint associated with it, Flann or Floinn, went blind in old age. According to local tradition, he did not pray for his own sight to be restored. Instead, he left the cure in the well for those who would come after him, a gesture of deliberate self-denial that gave the place its particular character.

The well sits on the side of a hillock beside the River Rae, near where it meets the River Shannow, in the townland of Shanavalla. Stones close to the water are said to be the remains of Saint Flann's hermitage, a small enclosure or cell of the kind used by early Irish monks seeking solitude. Tradition held that the saint came from County Clare, though neither his birthplace nor his burial place was remembered with any certainty. A large yew tree once grew over the well, its branches hung with offerings, cloth and flowers left by those who came to ask for relief. Earlier visitors would leave rags as votive offerings, a practice common at Irish holy wells and understood as a way of transferring illness or petition to the sacred site. The well appears on Ordnance Survey maps from 1841 to 1842 and again in the 1897 to 1898 revision under the name Toberflyn, the anglicised form of Tobar Flainn, meaning Flann's well. The local branch of Muintir na Tíre, a rural community organisation, remodelled the site in 1953, adding an alcove and a statue of Our Lady, and channelling what had been a spring issuing from a heap of stones into a spout feeding a concrete basin.

The day of devotion associated with the well is May Eve, the night before the first of May, which marks the old festival of Bealtaine. Visitors performing rounds, a traditional pattern of prayer involving circuits of a sacred site, were directed to begin at the well, move to the right up the small hill, walk around the well, and return to the starting point while reciting the Rosary. Schoolchildren collecting folklore in the area noted one particular custom: people of the parish did not drink the water as ordinary water, reserving it only for those occasions when they came specifically to visit the well.